To “tie” a pump to a specific mix-valve you must specify, in the mix-valve's settings, which pump you want it to control.

When you have a Mix-Valve type heating system, it is often necessary for the controller to manage the system pump(s).

For more details on this see the Programming / Mix Valve section of Help Desk. 

Here is a video - iGrow 1400 programming a Supply Pump

To Program your Pump, from home screen hit Enter/Menu -> Scroll and highlight Program Equipment hit Enter/Menu -> Once in equipment programming screen hit Enter/Menu to highlight output #in left Corner

** Note + & - allows you to navigate thru the outputs 1 thru 12 **

Once you have your output # highlighted that you want to program hit NEXT to high light the NONE Hit + to expand the NONE and + till you have Pump highlighted->then hit BACK button.

 in the programming you would assign a number, you can choose from 1 thru 12.  Now if you are using mix-valves on this controllers Network, the programming would need the pumps address if its to use this output as its supply pump.

Minimum % Open - If the mix-valve associated with this pump output opens beyond the Min Open % Value, this Pump output will turn on and remain on until the Mix Valve's percentage open has closed back below this threshold.  

In the example screen above, the pump will turn on when the mix-valve that it’s tied to opens at or above 5%.